The African coelacanth, a rare species that’s stayed much the same for the last 400 million years, has a lifespan of about 100 years, around five times longer than previously thought, according to a paper published yesterday (June 17) in Current Biology. Researchers used polarized light microscopy to examine scales collected from 27 fish captured between 1953 and 1991 and estimated, based on the structural patterns in the specimens, that the individuals ranged in age from 5 to 84 years.
“[The] coelacanth appears to have one of, if not the slowest, life histories among marine fish, and close to those of deep-sea sharks and roughies,” study coauthor Kélig Mahé of the North Sea Fisheries Research Unit in Boulogne-sur-mer, France, tells BBC News. “These new pieces of information on coelacanths’ biology and life history are essential to the conservation and management of this species.”
The African coelacanth, Latimeria chalumnae, was described in 1938 and is one of only two living species of coelacanth ever identified. It can grow up to two meters long, gives birth to live young, and is listed as critically endangered by the International Union for Conservation of Nature (IUCN).
Researchers have typically studied the age of these fish using light microscopes to count small lines on the animals’ scales that, like tree rings, represent growth periods and so can be used as a proxy for age. That method has in the past produced a coelacanth lifespan estimate of about 20 years.
Mahé and colleagues found that polarized light microscopy could reveal many more, thinner ridges that could also represent distinct periods of growth. Using this technique, they concluded that the true lifespan was likely closer to 100 years.
As part of their study, the team members analyzed the scales of embryos and estimated that they were around five years old, indicating “that the gestation duration is at least 5 years contrary to the 1 to 2 years suggested by earlier studies,” the researchers write in their paper.
Such a long gestation period is “very strange” for any animal, the Scripps Institution of Oceanography’s Harold Walker tells the Associated Press.
The team’s findings could aid coelacanth conservation, study coauthor Bruno Ernande of the University of Montpellier tells BBC News. “One very important framework for conservation measures is to be able to assess the demography of the species,” he says. “With this new information we will be better able to assess it.”